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In 1959, Neal Miller made the bold claim that the Stimulus-Response, Behaviorist models of that era were describing the way in which stimuli lead to the entry of contents into consciousness (entry, for short). Today, researchers have begun to investigate the link between external stimuli and involuntary entry, using paradigms such as the reflexive imagery task (RIT), the focus of our review. The RIT has revealed that stimuli can elicit insuppressible entry of high-level cognitions. Knowledge of the boundary conditions of the RIT effect illuminates the limitations of involuntary processes and the role of consciousness in the regulation of behavior. We review the boundary conditions of this paradigm as well as its systematic effects. Systematic effects are unlikely to be due to experimental demand. While reviewing each effect, we consider its theoretical implications. In addition, throughout our review, we discuss future directions for the study of insuppressible entry using the RIT. Last, we discuss a theoretical development (passive frame theory) that stems from the RIT and illuminates how involuntary entry and encapsulation, though at times disadvantageous for the actor, are essential for adaptive action selection during the course of ontogeny.

Laboratory tasks (e.g., the flanker task) reveal that incidental stimuli (e.g., distractors) can reliably trigger involuntary conscious imagery. Can such involuntary effects, involving competing representations, arise during dual-task conditions? Another concern about these laboratory tasks is whether such effects arise in highly ecologically-valid conditions. For example, do these effects arise from tasks involving dynamic stimuli (e.g., simulations of semi-automated driving experiences)? The data from our experiment suggest that the answer to our two questions is yes. Subjects were presented with video footage of the kinds of events that one would observe if one were seated in the driver's seat of a semi-automated vehicle. Before being presented with this video footage, subjects had been trained to respond to street signs according to laboratory techniques that cause stimulus-elicited involuntary imagery. After training, in the Respond condition, subjects responded to the signs; in the Suppress condition, subjects were instructed to not respond to the signs in the video footage. Subjects in the Suppress condition reported involuntary imagery on a substantive proportion of the trials. Such involuntary effects arose even under dual-task conditions (while performing the n-back task or psychomotor vigilance task). The present laboratory task has implications for semi-automated driving, because the safe interaction between driver and vehicle requires that the communicative signals from vehicle to driver be effective at activating the appropriate cognitions and behavioral inclinations. In addition, our data from the dual-task conditions provide constraints for theoretical models of cognitive resources.

The Reflexive Imagery Task (RIT) reveals that the activation of sets can result in involuntary cognitions that are triggered by external stimuli. In the basic RIT, subjects are presented with an image of an object (e.g., CAT) and instructed to not think of the name of the object. Involuntary subvocalizations of the name (the RIT effect) arise on roughly 80% of the trials. We conducted an electroencephalography (EEG) study to explore the neural correlates of the RIT effect. Subjects were presented with one object at a time in one condition and two objects simultaneously in another condition. Five regions were defined by electrode sites: frontal (F3-F4), parietal (P3-P4), temporal (T3-T4), right hemisphere (F4-P4), and left hemisphere (F3-P3). We focused on the alpha (8-13 Hz), beta (13-30 Hz), delta (0.01-4 Hz), and theta (4-8 Hz) frequencies.

Why does the general demeanor of others change as soon as they begin to "talk shop" or do something else that puts them into "work-mode"? We propose that such phenomena reflect an instance of incidental priming in which environmental cues activate actional "sets" formed through extensive training in a particular domain (e.g., music). Accordingly, we demonstrated that, by activating a "musician set," incidental musically-related stimuli prime musicians to spend more time on a domain-irrelevant task rehearsing nonsense words as compared to controls or non-primed musicians, as this set should involve a tendency towards deliberative practice. This finding provides additional evidence for a central tenet of social cognition research--that the mere presence of ambient stimuli influences behavioral dispositions systematically, in ways that often escape one's awareness. (Contains 1 figure.)

Does the mere presence of the things we have tended to influence our actions systematically, in ways that escape our awareness? For example, while entering a tool shed, does perceiving objects that we once tended to (e.g., tools, musical instruments) influence how we then execute a simple action (e.g., flicking the shed's light switch)? Ancient traditions (e.g., "feng shui") and contemporary approaches to action production (e.g., "continuous flow" and "cascade" models) hypothesize that the answer is yes. Although relevant to several fields (e.g., motor cognition, social cognition), for various reasons this hypothesis cannot be tested by traditional choice-response time interference paradigms, which involve more complex processes than our tool shed scenario. Using new paradigms that resemble detection tasks, three studies demonstrated that "very incidental" action-related distracters systematically interfere with simple, repeated actions that involve minimal response selection and decision-making processes. In Study 2, incidental musical notation interfered more with the simple actions of expert sight-readers than with the same actions of non-musicians. A similar pattern of effects was obtained with a fully experimental design. The implications for theories of action production, environmentally-driven automaticity, and social cognition are discussed. (Contains 6 figures and 1 table.)

Co-speech gestures traditionally have been considered communicative, but they may also serve other functions. For example, hand--arm movements seem to facilitate both spatial working memory and speech production. It has been proposed that gestures facilitate speech indirectly by sustaining spatial representations in working memory. Alternatively, gestures may affect speech production directly by activating embodied semantic representations involved in lexical search. Consistent with the first hypothesis, we found participants gestured more when describing visual objects from memory and when describing objects that were difficult to remember and encode verbally. However, they also gestured when describing a visually accessible object, and gesture restriction produced dysfluent speech even when spatial memory was untaxed, suggesting that gestures can directly affect both spatial memory and lexical retrieval.

High-level cognitions can be triggered into consciousness through the presentation of external stimuli and the activation of certain action sets. These activations arise in a manner that is involuntary, systematic and nontrivial. For example, in the Reflexive Imagery Task (RIT), subjects are presented with visual objects and instructed to not think of the names of the objects. Involuntary subvocalizations arise on roughly 80% of the trials. We review the findings from this paradigm, discuss neural findings that are relevant to the RIT, and present new data that further corroborate the reliability and robustness of the RIT, a paradigm that could be coupled with neuroimaging technologies. We developed an RIT variant in which two, non-focal objects are presented simultaneously. In previous RITs, visual objects were presented only one at a time, in the center of the screen, and subjects were instructed to focus on the center of the screen, where these objects were presented. Replicating the RIT effect, involuntary subvocalizations still occurred on a high proportion of trials (M = 0.78). An RIT effect arose for both objects on a considerable proportion of the trials (M = 0.35). These findings were replicated in a second experiment having a different sample of subjects. Our findings are relevant to many subfields of neuroscience (e.g., the study of high-level mental processes, attention, imagery and action control). [ABSTRACT FROM AUTHOR]

Spontaneous thoughts can arise from past memories, future tasks, and environmental cues. We developed a paradigm to investigate the stream of consciousness leading to spontaneous thoughts. While performing a concentration exercise (9 min) requiring one to focus only on one’s breathing, subjects observed spontaneous thoughts and counted the number of cognitions/percepts (‘links’) that they believed led to each spontaneous thought. In Studies 1–3, subjects reported less than 2 links per thought, over 80% of thoughts were attributed to a known cause, and roughly half of the thoughts were attributed to something outside the current environment. In Study 4, we examined the neural correlates of spontaneous thoughts triggered by external stimuli or internal, stimulus-independent factors (e.g., memories). Continuous EEG was recorded from seven active electrode sites (Fz, Cz, Pz, F3, F4, P3, and P4) as subjects indicated experiencing a thought. Subjects indicated whether their thoughts arose from internal (e.g., memories) or external (sights, sounds, smells, and bodily sensations) factors. To examine the neural correlates of each individually-reported thought, EEG was examined in short time scales (< 1 s) preceding each button press. Increased alpha correlation was observed for internal thoughts compared to a baseline condition (eyes-opened resting). In addition, increased alpha correlation in the parietal region was observed for internal compared to external thoughts. These findings are in line with previous research implicating distinct brain networks for internal and external awareness. We discuss the implications and potential future applications of this new approach for investigating the stream of consciousness. [ABSTRACT FROM AUTHOR]